<!DOCTYPE html>
<html>
<head>
    <title>Quirks Detection Example</title>
    <script type="text/javascript">
            
        var hasDontEnumQuirk = function(){
        
            var o = { toString : function(){} };
            for (var prop in o){
                if (prop == "toString"){
                    return false;
                }
            }
        
            return true;
        }();

        var hasEnumShadowsQuirk = function(){
        
            var o = { toString : function(){} };
            var count = 0;
            for (var prop in o){
                if (prop == "toString"){
                    count++;
                }
            }
        
            return (count > 1);
        }();

        alert(hasDontEnumQuirk);
        alert(hasEnumShadowsQuirk);
    </script>
</head>
<body>

</body>
</html>